Mechanisms and Consequences of TLR Signal Transduction

描述（由申请人提供）：哺乳动物 Toll 样受体 (TLR) 蛋白是多种微生物产物的模式识别受体。已鉴定出十种不同的 TLR 蛋白，这些蛋白相对于它们识别的配体来说似乎是非冗余的。不同的 TLR 激动剂在巨噬细胞和树突状细胞中诱导不同的基因表达模式，这表明先天免疫系统能够对所识别的病原体产生特异性反应。这种特异性的机制基础取决于各种 TLR 蛋白激活的信号转导途径的差异。 TLR 蛋白在人类和其他哺乳动物的先天免疫和适应性免疫水平的宿主防御中发挥着重要作用。这些受体在开发有效预防感染的疫苗中也发挥着关键作用。事实上，目前已知的许多最有效的疫苗佐剂都是 TLR 激动剂。已显示用确定的肽抗原进行免疫可引发Th1型和Th2型免疫应答，这取决于是否分别在TLR4或TLR2激动剂存在下施用抗原。因此，不同 TLR 蛋白引发不同基因表达模式的能力有助于定义感染或疫苗接种过程中引发的免疫反应的精确性质。这些拟议研究的总体目标是表征导致不同 TLR 激动剂诱导的不同基因表达模式的信号转导途径。我们的具体目标是： (1) 定义 TLR3 和 TLR4 细胞内信号传导域内的区域，这些区域是激活 NF-κB、MAP 激酶和细胞因子表达所必需的。 (2) 定义 TLR3 和 TLR4 细胞内信号传导域内激活 PKC-d 和 PI-3K 所必需的区域。 (3)评估TLR酪氨酸磷酸化的机制及其功能后果。

DESCRIPTION (provided by applicant): Mammalian Toll-like receptor (TLR) proteins are pattern recognition receptors for a diverse array of microbial products. Ten distinct TLR proteins have been identified, which appear to be non-redundant with respect to the ligands they recognize. Different TLR agonists induce distinct patterns of gene expression in macrophages and dendritic cells, suggesting that the innate immune system is capable of mounting a specific response to the pathogen being recognized. The mechanistic basis for this specificity depends on differences in signal transduction pathways activated by the various TLR proteins. TLR proteins play important roles in host defense at the levels of both innate and adaptive immunity in humans and other mammals. These receptors also play critical roles in the development of effective vaccines that protect against infection. Indeed, many of the most potent vaccine adjuvants currently know are TLR agonists. Immunization with a defined peptide antigen has been shown to elicit a Thl- and Th2-type immune response, depending on whether the antigen was administered in the presence of a TLR4 or a TLR2 agonist, respectively. Thus, the capacity of different TLR proteins to evoke distinct patterns of gene expression helps to define the precise nature of the immune response evoked during infection or vaccination. The overall objective of these proposed studies is to characterize the signal transduction pathways that lead to the distinct patterns of gene expression induced by different TLR agonists. Our specific aims will: (1) Define regions within the intracellular signaling domains of TLR3 and TLR4 that are necessary for the activation of NF-kappaB, MAP kinases, and cytokine expression. (2) Define regions within the intracellular signaling domains of TLR3 and TLR4 that are necessary for the activation of PKC-d and PI-3K. (3) Assess the mechanism of TLR tyrosine phosphorylation and its functional consequences.